Electronic memory system



P. PALlc ELECTRONIC MEMORY SYSTEM Sept. 30, 1958 2 Sheets--Sheet` 1 Filed Oct. 7, 1955 MTE lNvl-:NTOR

PE TA R PAL l c BY Z 2 2 A'Gerg JESS w HQW sept.V 3o, 1958 P. PAL@ 2,854,576

ELECTRONIC MEMORY SYSTEM United States Patent O ELECTRONIC MEMORY SYSTEM Petar Palic, Hamburg-Lockstedt, Germany, assignor, by

-mesne assignments, to North American Philips Company, Inc., New York, N. Y., a corporation of Delaware Application October 7, 1955, Serial No. 539,245

13 Claims. (Cl. Z50- 27) The present invention relates to electronic memory circuit arrangements. More particularly the invention relates to electronic memory systems more particularly for use in electronic calculating machines operating according to the decade system.

-ll Calculating machines of this kind are known in which the numbers to be handled are converted into corresponding pulse trains and supplied to an electron tube or a gas discharge tube, the discharge path of which can take up a number of predetermined stable positions and is moved by the pulses supplied to it each time from one stable position to the next succeeding stable position. Counting circuits have been designed which operate on this principle and which are capable of performing the operation of addition and, as the case may be, of subtraction.

ln such counting circuits advantageous use has been made of cathode ray tubes in which the electron beam can take up ten stable positions and is moved by a voltage pulse applied to a deflection plate each time from one stable position to the next succeeding stable position. The ten stable positions of the electron beam correspond to the digits to 9. Such tubes are commercially available, for example, under the type number ElT. This particular tube is described in an article in the Philips Technical Review entitled A decade counter tube by Van Overbeek,'et al., vol. 14, No. l1, May 1953. Counting tubes have also been designed in which a glow discharge is produced which can be displaced in the tube in direction from one electrode to another electrode by the application of corresponding voltage variations to the tube electrodes.

The invention is based on recognition of the fact that such tubes permit the constructing of numerical memory systems such as are used in a wide variety of forms in automatic calculating machines using the binary scale of notation. Such memory systems hitherto were designed either as ip-op ring circuits or the pulse groups corresponding to the numbers were registered magnetically, acoustically or electrostatically. These memory systems not only have to satisfy the requirements of high operating speed and dependable storage, but must also be capable of reproducing the stored information any number of times. In addition, the stored information must be readily erasable as the calculation proceeds and the properties of the numerical memory system must remain constant during operation with the minimum number of components.

The memory system in accordance with the present invention satisfies the above requirements and comprises a rst electron tube, or a gas discharge tube, the discharge path of which can take a number of predetermined stable positions and is displaced by the pulses (to ICC be stored) supplied to it each time from one stable posi-r out pulse train, which serves for reading out the stored pulse number and (in accordance with the decade system) consists of nine, for example, positive voltage peaks, is supplied to the control member of the second tube. The reading-out pulse train can only move the discharge path of the second tube a number of steps which is equal to the number of steps which the discharge path of the trst tube has moved under the action of the storing pulses supplied to it, the second tube each time supplying a pulse to the output terminals. In order to reset the position of the discharge path which is attained on reading out, the second tube has a, for example, negative reset pulse supplied to it. The reset pulse chronologically follows the reading out pulse train.

According to the invention, the memory system is preferably designed so that, in order to store a decimal number comprising at least two digits, for each decade stage a circuit arrangement is provided, comprising a rst and a second electron tube or gas discharge tube, in which arrangement the pulses supplied by the second tube on reading out are delayed in time, the delay the decade system) nine, for example, positive voltagepeaks. As has been mentioned above, a memory system in accordance with the invention is advantageously designed with the use of tubes of the type ElT. When use is made of these tubes lin which the electron beam can occupy ten stable positions, while at one of the deflection plates a voltage is produced which is characteristic'of the position occupied by the beam, the arrangement may be such that this voltage is supplied, preferably via a cathode amplifier stage which is directly coupled to the tube and via a diode, to the corresponding delection plate of the second tube so that the potential ofthe deection plate of the second tube cannot become more negative then that of the decction plate of the lirst tube. The pulse voltages are applied to the corresponding rst deection plates of both tubes, the pulses to bel stored being applied` to the rst deection plate of the tirst tube and the pulses of the reading-out pulse train being applied to the first' deflection plate of the second tube.

Preferably the arangement is ysuch that the de'ection plate of the second tube, which does not have the reading-out pulses applied to it, supplies the output pulses produced on reading-out to a time-delay network, preferably via a cathode amplier stage directly coupled to it, in which network said pulses are delayed in time so as to prevent them from coinciding with outputv pulses of other decade stages operating in parallel which might be read out at the same time.

In such memory systems, a pulse generator for the production of the reading-out pulse train may comprise a cascade arrangement of two trigger circuits, of which the rst, on reception of the reading-out control pulse, passes from one condition to the other while supplying a starting pulse to the second trigger circuit. As a result of the received starting pulse, the second trigger circuit Patented Sept. 30, 1958 starts to change its condition periodically at such frequency that at the end of the control pulse, when the first trigger circuit returns to the initial condition, the second trigger circuit has supplied the required number (in the decimal system, nine) of reading-out pulses. The arrangement may alternatively be such that the readingout control pulse may comprise a voltage peak of comparatively short duration, while the first trigger circuit has a comparatively large time constant. Thus, the first trigger circuit is triggered by the control pulse and simultaneously delivers the starting pulse to the second trigger circuit, and after a suitable period of time the iirst circuit automatically returns to the normal condition. During this period of time the second trigger circuit can produce the required nine reading-out pulses.

In a preferred embodiment, a reset pulse is derived from the output of the first trigger circuit by differentiation of the trailing edge of the reading-out control pulse or of the square-Wave voltage produced by the first trigger circuit, which reset pulse is supplied to the first grid of all the second cathode ray tubes of the individual decade stages.

In order that the invention may be readily put into elect, one embodimentthereof will now be described in detail with reference to the accompanying drawings, in which:

Fig. l is a schematic diagram of a preferred embodiment of the circuit arrangement of the present invention; and

Fig. 2 is a schematic diagram of a preferred embodiment of the circuit arrangement of an associated pulse generator for the production of the reading-out pulse train.

In the memory decade stage shown in Fig. l, use is made of two tubes of the type ElT for storing and reading out, respectively. The decade stage comprises two counting tubes 2 and 3, of the said type, which are coupled to one another via a cathode amplifier stage 1 and a ipop circuit comprising tubes 4 and 5. The circuit 4, 5 serves to shape the pulses produced by the tube 3 into a true square-wave form and to delay them in time.

As is well-known, the decade-system counting tube EIT is a cathode ray tube having ten stable positions for the deflection of the cathode ray. Under the action of pulses of predetermined voltage and shape, which are supplied to one deflection electrode, the cathode ray passes from one stable position to the next succeeding stable position. This cathode ray deflection is associated with a potential drop of the other deflection plate. This potential may have the following values for indicating the number:

'Number` 0123456789 Voltage The mean value of the voltage variation from one position to another position is approximately l5 volts.

The input circuit of the counting tube 2 is provided with two input terminals 6 and 6. The counting pulses to be stored are directly supplied to the terminal 6 Whereas the pulses from the next preceding counting decade stage are supplied to the terminal 6'. The deflection plate of the tube 2 to which the counting pulses must be supplied is preceded by a double diode 7 which is connected so that the two terminals 6 and 6 are decoupled from one another. When a counting pulse appears at the terminal 6, the upper diode path becomes conductive and the pulse is set up at the deflection plate of the tube 2. Simultaneously, the potential of the common diode cathode is more positive than that of the anode of the second diode path. This prevents the counting pulse from entering the lead connected to the terminal 6. When a pulse appears at the input terminal 6', the circuit arrangement operates accordingly.

When, for example, a pulse train comprising seven counting pulses appears at the deection plate of the tube 2, the second deection plate of the tube 2 has a potential of 140 volts in accordance with the above table. This potential is applied to the grid of the tube 1, which is directly coupled to the tube 2 and acts as a cathode amplier. When the cathode resistance of the tube 1 is given a proper value, the cathode potential of said tube corresponds to the potential of the second deflection plate of the tube 2. A diode 8 is connected between the cathode of the tube 1 and the second deflection plate of the tube 3. The provision of the diode 8 at this point in the circuit arrangement ensures that the potential of the second deection plate of the tube 3 cannot be driven more negative than the potential of the second deliection plate of the tube 2. lf, now, a pulse train comprising nine positive voltage peaks is supplied to the iirst deliection plate of the tube 3, as must be the case whenever a stored number is to be read out, the cathode ray of the tube 3 is initially caused to move stepwise by said nine reading-out pulses, but it can only attain the seventh step. Every further step is prevented by the fact that the diode 8 is becoming conductive, which diode connects the second deflection plate of the tube 3 to the cathode of the tube 1, said cathode having a comparatively low ohmic resistance.

When the diode 8 has not yet become conductive, i. e. during the lrst seven reading-out pulses, sudden changes of voltage, similar to those already mentioned with reference to the tube 2, arc produced at the second deflection plate of the tube 3. These seven voltage variations are supplied via another directly coupled cathode ampliier stage, which includes an electron tube 9, to an RC circuit 10, 11 which serves as a dierentiating circuit. Due to seven steps of the cathode ray in the tube 3, at the differentiating circuit 10, 11 seven negative-going pulses are produced which are supplied to a tiip-op circuit comprising tubes 4, 5 via a diode 12. The diode 12 has a bias voltage of approximately seven volts applied to it, so that the flip-hop stage 4, S is triggered only by pulses which are supplied from the tube 3.

When numbers comprising at least two digits must be stored, a plurality of such decade stages must be provided, since the circuit arrangement shown in Fig. l only permits the storing of digits between O and 9. In other decade stages the pulse counting operation is performed so as to be parallel in time. If, for example, the number 731 must be stored, provision must be made of three decade stages, one for hundreds, one for tens, and one for units. When the digits stored in the individual decade stages are read out, each decade stage only passes part of the readingout pulses in the manner described. Thus, when the number 731 has been stored, the hundreds stage passes seven pulses, the tens stage passes three pulses and the unit stage passes one pulse. Further manipulation of these numbers taken from the memory system requires that the pulse trains from they individual decade stages be non-coincident. This may be ensured by a proper choice of the grid time constants in the ip-flop circuits comprising the tubes 4 and 5 which follow the dir"- ferentiating circuit 10, 11. Consequently, the hip-hop stages of the individual decade stages must be designed so that they deliver the output pulses with time delays of diiferent duration.

When a number of storing pulse trains are supplied in succession to the same storing decade stage, that is, when an addition must be performed in the memory system, provision is made, in addition to the counting tube 2, of another Hip-flop circuit comprising electron tubes 20 and 21. When the second counting pulse train supplied to 'the tube 2 together with the iirst train [which has already been stored] produces a sum number exceeding ten, a pulse appears at the electrode 22 of the tube 2, when the tenth counting step'is attained. The pulse at electrode 22 causes the Hip-flop circuit 20, 21 to pass from one condition to the other. The voltage variation produced at the anode of the tube 21 is transmitted to the first grid of the tube 2 and causes the electron beam of said tube to return to the zero position. Simultaneously, at the cathode of the two tubes 20, 21 a pulse is set up which, via terminal 23, is supplied to the next higher decade stage, more particularly to the terminal 6 thereof. Thus, the pulse transmitted from terminal `23 ensures that when the numerical value ten is exceeded, the next higher decade stage is correctly switched one step.

Each reading-out pulse from the calculating system provided with a memory system in accordance with the invention produces the required pulse train. The readingout pulse train is simultaneously supplied to the tubes 3 of the various decade stages. The generator for the reading-out pulse train according to Figure 2 consists of two Hip-flop stages comprising the tubes 13 and 14, 15 and 16. If required, at the input 17 of the generator, a reading-out control pulse is set up which causes the rst flip-Hop circuit 13, 14 to change from one condition to the other. The starting impulse appearing at the anode of the tube 14 and transmitted to the grid of the tube 15 is of such duration that during this period of time the second trigger circuit 15, 16, which is triggered by it, is enabled to produce nine uniformly spaced reading-out pulses.

Thus, when the rst ip-op circuit 13, 14 changes ,from one condition to the other, a positive pulse is set up at the anode resistance of the tube 14. This sudden potential variation is directly supplied to the control grid of the tube 15 via a voltage divider. Said voltage divider is so proportioned that the control grid of the tube 15 is driven positive to an extent such that the tubes 15, 16 start to change from one condition to the other periodically.

A proper choice ofthe value of the time constant of the circuit connected between the anode of the tube 15 and the control grid of the tube 16 ensures that the said two tubes change from one condition to the other nine times during the pulse supplied from the anode of the tube 14. Consequently, nine positive going pulses are produced across the anode resistance of the tube 16. These pulses are differentiated and the negative voltage peaks of these pulses are then clipped and are thus given the proper shape for controlling the tube 3 of Fig. l; said pulses being supplied to the first deection plate of said tube through'the lead 19.

After each reading-out process the tubes 3 (Fig. l) must be reset, since the cathode ray remains directed to the last digit to be counted. For this purpose the anode pulse of the tube 14 (Fig. 2) is differentiated and the positive voltage peak thus produced is clipped. Thus, the negative-going pulse which remains is transmitted through the lead 18 to the rst grid of the tube 3 and to the corresponding grids of the remainder of the decade stages which operate in parallel. The reset pulse is delayed in time in relation to the ninth reading-out pulse. When a further reading-out control pulse follows immediately after the reading-out process described above, the reset pulse must be set up an instant after the production of the ninth pulse of the irst reading-out pulse train and after the rst pulse of the next reading-out train.

What is claimed is:

l. A circuit arrangement comprising iirst and second electron discharge tubes of the type having an electron discharge adapted to be moved from an initial stable position to a resultant stable position through a plurality of consecutive intermediate stable positions, means for moving said electron discharge from its initial stable position and means for deriving from said electron discharge an indication of its resultant stable position, means for applying a rst train of pulses to be stored to the discharge moving means of said first tube thereby to move the discharge of the said rst tube to a resultant position indicative of a number to be stored in the said iirst tube,

means for applying a second `train of reading-out pulses to the discharge moving Ameans of said second tube thereby to move thev discharge of the said second tube fromA its initial position, means for coupling the position indication means of said first tube to that of said second tube thereby to limit movement of the discharge of the said second tube by said second train of pulses to the same resultant stable position as that of the said rst tube, means for deriving from said second tube an output signal indicative of its resultant stable position, and means for moving the discharge of 4said second tube to its initial position at a time after the application of said second train of pulses.

2. A circuit arrangement as claimed in claim l, further comprising time delay means for delaying the output signal derived from said second tube thereby permitting said circuit arrangement to be cooperatively combined with a plurality of similar circuit arrangements to produce a single series of output signals which is indicative of a train of pulses applied to all the said circuit arrangements in common without undesired coincidence of the said output signals.

3. A circuit arrangement as claimed in claim l, wherein said second pulse train applying means comprises a pulse generator having an input and an output, means for applying an input control pulse to the input of said pulse generator and means for deriving from the output of said pulse generator a series of output pulses when said input control pulse is applied thereto, the said series of output pulses comprising a number of pulses suicient to move the discharge of said second tube through all of its stable positions.

4. A circuit arrangement as claimed in claim l, wherein said 'second pulse train applying means comprises rst and second trigger circuits each having two stable operating conditions, an input and an output, means for applying an input control pulse to the input of said iirst trigger circuit thereby to change said first trigger circuit from its l initial stable condition to its other stable condition, and means for coupling the input of said second trigger circuit to the output of said first trigger circuit thereby causing thesaid second trigger circuit to alternately change from one stable condition to the other to generate a series of output pulses when said input control pulse is applied to the said irst trigger circuit, the said series of output pulses comprising a number of pulses sucient to move the discharge of said second tube through all of its stable positions by the time the said first trigger circuit returns to its initial stable condition.

5. A circuit arrangement as claimed in claim 4, wherein each of said electron discharge tubes further comprises electrode means for moving said electron discharge to its initial position and wherein said means for moving the discharge of said second tube to its initial position comprises diierentiating means having an input connected to the output of the said rst trigger circuit and an output, clipping means, and means for coupling the output of said differentiating means to the electrode means for moving the discharge to its initial position of the said second tube through said clipping means. p

6. A circuit arrangement comprising rst and second electron discharge tubes of the type having an electron discharge adapted to be moved from aninitial stable position to a resultant stable position through a plurality of consecutive intermediate stable positions, means for moving said electron discharge from its initial stable position and means for deriving from said electron` discharge an indication of its resultant stable position, means for applying a rst train of pulses to be stored to the discharge moving means of said rst tube thereby to move the discharge of thel said rst tube to -a resultant position indicative of a number to be stored in the said first tube, means for applying a second train of readingout pulses to the discharge moving means of said second tube thereby to move the discharge of the said second 7 tube from its initial position, means for coupling the position indication means of said first tube to that of said second tube thereby to limit movement of the discharge of the said Second tube by said second train of pulses to the same resultant stable position as that of the said first tube, said coupling means comprising a cathode amplifier having an input directly coupled to the said position indication means of the said first tube and an output, a diode and means for coupling the output of said cathode amplifier to the said position indication means of the said second tube through said diode whereby the potential of the said position indication means of the said second tube is prevented from becoming more negative than that of the said position indication means of the said first tube, means for deriving from said second tube an output signal indicative of its resultant stable position, and means for moving the discharge of said second tube to its initial position at a time after the application of said second train of pulses.

7. A circuit arrangement as claimed in claim 6, wherein said output signal deriving means comprises a second cathode amplifier having an input directly coupled to the said position indicating means of said second tube and an output, time delay means, means for coupling the output of said second cathode amplifier to said time delay means and means for deriving the said output signal from the said time delay means.

8. A circuit arrangement comprising first and second electron discharge tubes of the type having an electron discharge adapted to be moved from an initial stable position to a resultant stable position through a plurality of consecutive intermediate stable positions, the total of said stable positions being ten, first electrode means for moving said electron discharge from its initial stable position, second electrode means for deriving from said electron discharge an indication of its resultant stable position and third electrode means for moving said electron discharge to its initial position, means for applying a first train of pulses to be stored to the first electrode means of said first tube thereby to move the discharge of the said first tube to a resultant position indicative of a number to be stored in the said first tube, means for applying a second train of reading-out pulses to the first electrode means of said second tube thereby to move the discharge of the said second tube from its initial position, means for coupling the second electrode means of said first tube to that of said second tube thereby to limit movement of the discharge of the said second tube by said second train of pulses to the same resultant stable position as that of the said first tube, said coupling means comprising -a cathode amplifier having an input directly coupled to the said second electrode means of the said iirst tube and an output, a diode and means for coupling the output of said cathode amplifier to the said second electrode means of the said second tube through said diode whereby the potential of the said second electrode means of' the said second tube is prevented from becoming more negative than that of the said second electrode means of the said first tube, means for deriving from said second tube an output signal indicative of its resultant stable position, and means for moving the discharge of said second tube to its initial position at a time after the application of said second train of pulses.

9. A circuit arrangement as claimed in claim 8, wherein said output signal deriving means comprises a second cathode amplifier yhaving an input directly coupled to the said second electrode means of said second tube and an output, time delay means, means for coupling the output of said second cathode amplifier to said time delay means and means for deriving the `said output signal from the said time delay means.

l0. yA circuit arrangement comprising first and second electron discharge tubes of the type having an electron discharge adapted to be moved from an initial stable position to a resultant stable position through a plurality of consecutive intermediate stable positions, the total of said stable positions being ten, first electrode means for moving said electron discharge from its initial stable position, second electrode means for deriving from said electron discharge an indication of its resultant stable position and third electron means for moving said electron discharge to its initial position, means for applying a first train of pulses to be stored to the first electrode means of said first tube thereby to move the discharge of the said first tube to a resultant position indicative of a number to be stored in the said first tube, means for applying a second train of reading-out pulses to the first electrode means of said second tube thereby to move the dischargerof the said second tube from its initial position, means for coupling the second electrode means of said first tube to that of said second tube thereby to limit movement of the discharge of said second tube by said second train of pulses to the same resultant stable position as that of the said first tube, said coupling means comprising a first cathode amplifier having an input directiy coupled to the said second electrode means of the said first tube and an output, a diode having one terminal connected to the output of said first cathode amplifier and a second cathode amplifier having an input directly coupling the said second electrode means of said second tube to the other terminal of said diode and an output whereby the potential of the said second electrode means of the said second tube is prevented from becoming more negative than that of the said second electrode means of the said first tube, means for deriving from said second tube an output signal indicative of its resultant stable position comprising said second cathode amplifier, a differentiating circuit, a trigger circuit having two stable operating conditions and an inherent time delay, said trigger circuit having an input and an output, means for coupling the output of said second cathode amplifier to the input of said trigger circuit through said differentiating circuit and means for deriving the said output signal from the output of the said trigger circuit, and means for moving the discharge of said second tube to its initial position at a time after the application of said second train of pulses.

1l. A circuit arrangement as claimed in claim l0, wherein said second puise train applying means comprises second and third trigger circuits each having two stable operating conditions, an input and an output, means for applying an input control pulse to the input of said second trigger circuit thereby to change said second trigger circuit from its initial stable condition to its other stable condition, and means for coupling the input of said third trigger circuit to the output of said second trigger circuit thereby causing the said third trigger circuit to alternately change from one stable condition to the other to generate a series of output pulses when said input control pulse is applied to the said second trigger circuit, the said series of output pulses comprising a number of pulses sufficient to move the discharge of said second tube through its ten stable positions by the time the said second trigger circuit returns to its initial stable condition.

l2. A circuit arrangement as claimed in claim ll, wherein said means for moving the discharge of said second tube to its initial position comprises a second difierentiating circuit having an input connected to the output of the said second trigger circuit and an output, a clipping circuit, and means for coupling the output of said second differentiating means to the third electrode means of the said second tube through said clipping means.

13. A circuit arrangement as claimed in claim l2, wherein said first tube further comprises fourth electrode means for indicating when said electron discharge is in the stable position farthest from its initial position, and further comprising a fourth trigger circuit having two stable operating conditions, an input and an output, means for coupling the fourth electrode means of said first tube to 'the input of said fourth trigger circuit thereby to change 2,854,576 9 10 the said fourth trigger circuit from its initial stable conmove the electron discharge of the said first tube to its dition to its other stable condition upon the reaching of its initial position. farthest stable position by the said electron discharge,

means for deriving from the output of the said fourth References Cited m the me of thls Patent trigger circuit a control signal generated upon the said 5 UNITED STATES PATENTS change of stable condition of the said fourth trigger cir- 2,679,978 Kandiah June 1, 1954 cuit and means for applying said control signal to the 2,714,179 Thomas et al July 26, 1955 third electrode means of the said rst tube thereby to 2,745,958 Depp May 15, 1956 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No 854,576 September 30, 195

Petar Palio It is hereby Certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected belowJ in the heading to the printed specifications, between lines 6 and '7, insert D Claims priority, application Germany November 26, 1954 we Signed and sealed this 13th day of January 1959o (SEAL) Attest:

KARL H AXLINE ROBERT c. WATSON 'ttesbing Officer Commissioner of Patents 

